The identification of indigenous plant growth-promoting bacteria (PGPB) from the Qinghai-Tibet Plateau is vital for developing region-specific microbial inoculants to improve crop productivity in high-altitude agricultural ecosystems. The solubilizing strains were isolated from faba bean leaves and roots collected in alpine farmlands of Qinghai using selective media. Following this, multifunctional PGPB with plant growth-promoting traits and biocontrol activities were identified. Selected PGPB strains were introduced into the rhizosphere of tomato plants to assess their impact on growth promotion. Results revealed that strain H18 displayed nitrogen fixation, phosphorus and potassium solubilization, IAA production, and ACC deaminase activity. Additionally, it also exhibited antagonistic effects against eight fungal plant pathogens. Physiological and molecular analyses identified strain H18 belongs as Bacillus atrophaeus. This strain significantly improved tomato seed germination and enhanced growth during seedling and flowering stages, including parameters such as plant height, crown width, and stem diameter. Furthermore, during the fruiting stage, it increased yield and improved fruit quality. In conclusion, strain H18 is a multifunctional PGPB with excellent biocontrol and growth-promoting effects.

ABSTRACT The excessive use of agrochemicals, especially pesticides, has resulted in their accumulation in crops and the environment, raising concerns for both soil health and microbial inoculant performance. This study evaluated the tolerance and functional efficacy of functionally characterized heterotrophic sulfur‐oxidizing plant growth‐promoting bacteria (SOB) in the presence of five commercial pesticides—herbicides (pendimethalin and clodinafop), fungicides (bavistin and ridomil), and an insecticide (chlorpyrifos)—at recommended and sublethal concentrations (0.5 minimum inhibitory concentrations [MICs]). Three strains, Enterobacter ludwigii Remi_9, Enterobacter hormaechei AUH‐ENM30, and Bacillus sp. 5BM21Y12, were obtained from the Department of Microbiology, Punjab Agricultural University, Ludhiana, India. All strains exhibited good growth at recommended pesticide doses except with ridomil. Growth profiling revealed that Bacillus sp. achieved the highest OD 540 nm at clodinafop (2.09), isoproturon (2.44), bavistin (1.46), and chlorpyrifos (0.88), whereas E. hormaechei showed optimum growth (OD 540 nm 2.24) with pendimethalin. E. ludwigii recorded peak growth (OD 540 nm 1.68) at 0.5 MIC of ridomil. Functional characterization indicated that Bacillus sp. showed highest phosphate solubilization (1.76 µg/mL), IAA production (38.43 µg/mL), siderophore production (12.70 µg/mL), ammonia excretion (3.03 µg/mL), and sulfate production (0.12 mM). E. ludwigii excelled in qualitative phosphate and zinc solubilization, whereas E. hormaechei produced the highest siderophores. This study represents the first detailed reports from India on pesticide tolerance of functionally characterized heterotrophic SOB strains with multiple plant growth‐promoting traits, highlighting their potential as sustainable bioinoculants for improving crop productivity under pesticide‐impacted environments.

Traditional Indian bioformulations such as Panchagavya, Jeevamrit, Beejamrit, Matka-khad, and others have long provided sustainable, eco-friendly means to enhance crop growth and protection by using natural materials. In this study, fermented bioformulations based on cow dung and urine from indigenous and exotic cow breeds were compared for plant growth-promoting (PGP) traits, antifungal and enzyme activities to support sustainable agriculture. Physico-chemical analysis revealed that bioformulations made with the indigenous Pahari breed had the highest N, P, K values: Jeevamrit (N 0.232%, P 0.050%, K 0.086%), Beejamrit (N 0.483%, P 0.124%, K 0.297%), Ghanjeevamrit (N 1.38%, P 0.468%, K 0.993%) and Matka-khad (N 0.995%, P 0.051%, K 0.226%). Among microbial counts, Pahari lactating bioformulation showed the maximum (28.5 × 10⁶ cfu/ml), followed by Pahari dry (27.8 × 10⁶ cfu/ml), while Sahiwal dry showed the least (24.5 × 10⁶ cfu/ml). The bacterial isolates from these bioformulations displayed all the PGP traits tested- nitrogen fixation, phosphorus solubilization, siderophore production, and IAA production- except for HCN production. Out of 18 promising isolates, 11 showed antifungal activity against one or more fungal pathogens. For example, GPB2 inhibited Sclerotinia sclerotiorum by 50%, GJD1 had an 83.93% inhibition rate against Pythium aphanidermatum, JPL6 gave 43.72% inhibition versus Phytophthora sp., GPD3 showed 56.50% against Rhizoctonia solani, GJD1 gave 21.5% inhibition against Alternaria alternata, and some isolates only showed contact inhibition against Fusarium oxysporum. Overall, GJD1 was the most active isolate across many pathogens, except Phytophthora spp. Pot experiments further confirmed that non-autoclaved bioformulations (i.e. those retaining live microbes) led to superior growth results. Chemical characteristics of fermented bioformulations showed maximum N, P and K content in non-autoclaving treatment T2 (Pahari dry). Treatment T1 (Pahari lactating), T5 (Jersey lactating), and T7 (Pahari bull) achieved 100% germination. Treatment T2 (Pahari dry) showed highest vigour index (34.54). Root and shoot weights were greatest in T6 and T5 (Jersey dry & lactating) with 4.23 g and 7.59 g plant-1, respectively. The highest number of nodules per plant (21) was observed in T6 which was statistically at par with T1 and T7 (Pahari bull). Dry matter content (10.91 g plant-1) in T5 and pods per plant (14) in T12. Yield peaked at 58 g plant-1 in T5. Nutrient content of soil in T2 was remarkable: N (246.7%), P (18.6%), and K (209%). Soil microbial population was highest in T1, with 4.30 × 10⁸ cfu g-1 soil. The 18 promising PGP strains were also identified via 16 S rRNA gene sequencing. We conclude that bioformulations made using indigenous Pahari and Jersey lactating cow breeds outperform other breeds irrespective of lactating or not for use in natural farming systems. Furthermore, these identified bacterial strains, when used along with the bioformulations, could enhance productivity, improve soil health, and aid in disease management.

Background.Globally, seagrass ecosystems are threatened by anthropogenic activities that are leading to increased levels of eutrophication, coastal pollution and thermal conditions. Consequently, there is a growing need to develop new approaches that work to mitigate these stressors and enhance restoration efforts in seagrass meadows. One promising strategy is to identify, isolate and characterize microbial consortia that are likely to support seagrass productivity. However, our current understanding of key microbial functions that support plant growth in marine systems is limited. Based on evidence from terrestrial plant-microbe systems, seagrass-associated bacteria are expected to provide the plant with nitrogen and phosphorus resources while detoxifying sulfur and producing phytohormones. Here, we sequenced 61 bacterial cultures isolated from the rhizosphere, rhizoplane, and endosphere of the seagrass, Zostera marina to identify a consortium of six putative plant growth promoting (PGP) candidates.Results.Our cultivation approach using plant-based media allowed us to isolate 201 bacteria from Z. marina, which reflected 18% of the total microbial diversity of the starting inoculum. Genomic and phenotypic analyses of the 61-sequenced pure-cultures revealed that most of the sequenced taxa were able to mobilize nitrogen primarily through catabolic pathways, including denitrification (51%), dissimilatory nitrate reduction to ammonia (71%), and C-N bond cleavage (83%). Six of the isolates, which represent new lineages of Agarivorans, coded for the nitrogenase gene cassette. Additionally, 52% of the genomes had genes for sulfur and/or thiosulfate oxidation, 88.5% for phosphorus solubilization, and 60.5% for IAA production. Genomic analysis also revealed that some pathways, including denitrification and dissimilatory nitrite to ammonia DNRA, required cross-species cooperation as no one taxa contained all the genes needed to complete these metabolic pathways. Based on draft genome models and results from phenotypic assays, isolates Streptomyces sp. (Iso23 and Iso384), Mesobacillus sp (Iso127), Roseibuim sp. (Iso195), Peribacillus sp. (Iso49), and Agarivorans sp. (Iso311) represent a minimal microbial community that is likely to promote seagrass growth and enhance restoration efforts.Conclusion.Our work provides a detailed genomic and phenotypic analysis of bacteria isolated from Z. marina and identifies a minimal microbial community with complementary PGP traits. Isolating, identifying and characterizing bacteria that promote seagrass growth is critical towards enhancing restoration efforts of seagrass meadows.

Glyphosate is a widely used broad-spectrum systemic herbicide that effectively controls weeds by inhibiting the synthesis of specific amino acids for the formation of plant proteins. Improper and repeated use can lead to the accumulation of residue in the soil, which may remain strongly absorbed over an extended period. Investigations into the biodegradation of glyphosate in soil under various environmental conditions are crucial for bioremediation efforts. Recently, a further step has been taken considering the use of rhizobacteria for the removal of glyphosate herbicide. Our research aimed to isolate naturally occurring rhizobacteria from Tithonia diversifolia (as a source of green manure) and assess the critical ecological factors influencing their growth and glyphosate degradation. Screening began by cultivating a one gram of T. diversifolia rhizosphere soil sample in Nutrient Broth (NB) media containing 15 mg mL−1 glyphosate for a week. The six isolates initially obtained were further subcultured in Nutrient agar (NA) containing nutrient agar and 15 mg mL−1 glyphosate. The morphological and physiological properties, phosphate solubilization, and IAA production were used in isolate characterization, in addition to glyphosate biodegradation. Only two isolates, TBr1 and TBr12, have shown the capacity to survive and biodegrade glyphosate. Both isolates exhibit optimal pH levels above 6.0 and optimal activity at 30 °C, demonstrating the fastest growth rates and abilities to break down glyphosate by 67% and 76%, respectively, within 7 days. Tested in a medium minus carbon, nitrogen, and phosphorus sources, both isolates showed the ability to hydrolyze glyphosate through CN and CP bonds. However, they had different CP lyase efficacy in metabolizing glyphosate. Based on 16S rDNA gene sequence analysis, TBr1 was identified as Burkholderia cepacia strain TBr1, and TBr12 as the Bacillus velezensis strain TBr12. Therefore, the ability of both isolates to degrade glyphosate, produce IAA, and dissolve phosphates makes them promising candidates for removing these emerging contaminants from the environment. HIGHLIGHTS Glyphosate inhibits EPSP synthase, potentially damaging the microbiome and soil ecosystems. The research focus is on the isolation and characterization of glyphosate-degrading rhizobacteria from Tithonia diversifolia. The strains Burkholderia cepacia TBr1 and Bacillus velezensis TBr1 hydrolyze glyphosate by 67% and 76%, respectively, within one week at a concentration of 15 mg mL-1. Both strains have the potential to serve as bioremediation agents for glyphosate contamination. GRAPHICAL ABSTRACT

The banana Fusarium wilt pathogen, Fusarium oxysporum f. sp. cubense ( Foc ), is a major threat to banana production globally. In India, Foc race 1 and tropical race 4 (TR4) are reported from multiple banana-growing states where it causes severe yield losses. To develop integrated approaches, in the present study the effect of organic amendments, water logging and paddy rice cultivation on Fusarium wilt development was assessed. Cavendish cv. Grand Nain (AAA) bananas were grown in small plots and pots in soils with organic amendments. Of the organic amendments, groundnut and gingelly cakes applied at 300 g per plant fully suppressed Fusarium wilt caused by Foc TR4, with an internal wilt disease score of 0 on a 0–5 scale, while groundnut and neem cake strongly suppressed the disease, with disease scores of 0.3-0.33 at the same concentration in plants infected with Foc race 1. Plant growth parameters (height, girth, number of leaves, and leaf area) were also significantly increased for plants treated with groundnut cake ( Foc TR4 - inoculated plants) and neem cake ( Foc race 1-inoculated plants). The neem cake application significantly increased the fungal (up to 7x10 10 cfu/g), bacterial (up to 33x10 10 cfu/g of soil) and actinomycetes (up to 4x10 6 cfu/g) numbers in soil compared to soil without the organic amendment. In vitro evaluation of 49 bacterial and 14 fungal isolates identified six Bacillus and five Trichoderma spp. as highly suppressive to Foc TR4, with enhanced protease and cellulase activities and IAA production, indicating both pathogen suppression and plant growth–promoting mechanisms. Waterlogging and paddy rice cultivation under micro-plot conditions for 4 months reduced Fusarium wilt (TR4) severity to score of 2.2 and 1.13, respectively, on a 0–5 rating scale, compared with the control treatment, which recorded severity scores of 3.4 and 3.5, respectively. qPCR analysis revealed that pot soils amended with groundnut cake reduced Foc TR4 and race 1 DNA by 90.6% and 81.2%, respectively, while mustard and gingelly cakes reduced Foc TR4 by 86.9% and 84.5%, respectively, and neem cake reduced Foc race 1 by 85.1%. The waterlogging for 4 months and paddy rice cultivation in micro plots resulted in even greater reductions of Foc TR4 DNA by 98.1% and 97.8%, respectively. These results suggest that organic amendments, flooding, and paddy rice cultivation could be effective strategies for managing Fusarium wilt of banana in the field.

Rhizome rot disease caused by Fusarium solani severely limits turmeric (Curcuma longa L.) productivity. This study aimed to isolate endophytic bacterial strains from turmeric roots and screen them for plant growth-promoting (PGP) traits and antifungal activity. Among 10 isolates, strain TuR6, identified as Bacillus cereus (98.68% similarity, GenBank accession: PV565573), showed the highest IAA production (75.41 mg/L), strong phosphate solubilization (PSI 5.32), and positive siderophore, protease, and cellulase activities. TuR6 inhibited F. solani growth by 78.12% in vitro. In greenhouse trials, TuR6 significantly increased plant height (80.57 cm), rhizome yield (371 g/plant), and reduced disease incidence (17.7%). Field experiments confirmed its efficacy, with notable growth and disease suppression improvements under natural conditions. These results highlight B. cereus TuR6 as a potential bioinoculant for enhancing turmeric yield and managing rhizome rot sustainably.

Bacteria represent promising tools for reducing the use of synthetic inputs in crop production. In this study, we evaluated the effects of two bacterial strains isolated from chicken compost tea—Bacillus licheniformis and Pseudomonas mendocina—on the yield and quality of strawberry. Experimental assays were conducted in two seasons (2023 and 2024) under macro-tunnel conditions, with the following treatments: control without applications (Con); commercial NPK fertilizer (FerC); application of B. licheniformis (BL) and P. mendocina (PM) solution in soil once a month. Both bacterial treatments enhanced soil properties. Fruit individual weight significantly increased in BL treatment compared to the control. Similar trends were observed for anthocyanin and ascorbic acid content (increases > 25%), as well as for antioxidant activity (increases of more than 20% and 13% for BL and PM, respectively). The differences were more significant in 2023. In addition, both strains showed positive in vitro results for phytase, siderophore, and IAA production (5.8–8.8 and 9.3–13 µg IAA/mL for BL and PM after 15 days). Although further field validation is required, these results indicate that bacteria (particularly B. licheniformis) show strong potential as bioinoculants to enhance the productivity and quality of strawberry.

Indole-3-acetic acid from plants and microbes inhuman health.

Jeevamrit, a microbial inoculant widely used in zero-budget natural farming (ZBNF) that relies on local farm-based resources to enhance overall biological health of soil, is reported for inconsistent crop yield enhancements. This is mainly due to variability in its preparation methods, e.g., mixing intensity, incubation regimes, and quality of ingredients used. Hence, the current study aimed to decipher the effect of mixing intensity (extent of oxygenation) on microbial community composition, nutrient transformation, and plant growth attributes of Jeevamrit, using a combined metagenomics-culturomics approach. Frequent mixing (Constant/Intermediate) enhanced nutrient solubilization (Fe, Zn, Cu, Mn) with higher total N and dissolved organic carbon, while less mixing (Anoxic/No-mix) led to accumulation of soluble Fe and NH₄⁺-N with higher microbial diversity. Mixing-driven differential enrichment of taxa were noted, i.e., constant mixing (CM) dominated by Acinetobacter (~ 40%), Comamonas, Pseudomonas, and Lysinibacillus, linked to oxidative C/N cycling and metal dissolution. Whereas, anoxic (AO) favored Clostridium sensu stricto, Lactobacillales, Enterococcus, and Enterobacterales (> 60%), correlating to fermentative metabolism-driven reductive elemental cycling. Co-occurrence network analysis identified Acinetobacter, Pseudomonas, Comamonas, Trichococcus, and Stenotrophomonas as hubs, indicating keystone functions in structuring metabolic interactions. The metagenome-recovered MAGs belonged to Acinetobacter sp., Clostridium saccharobutylicum, Trichococcus flocculiformis, and Enterococcus gallinarum with potential to participate in multiple nutrient cycling. Cultivable members of Shigella, Rhodococcus, and Bacillus spp. showed high IAA production (135-145µg mL⁻1), NH₃ release (~ 0.12µg mL⁻1), and K and P solubilization (~ 55.2µg mL⁻1). We hypothesize that oxygenation drives the Jeevamrit's microbial guild assembly, where mixing intensity modulates oxido-reductive metabolism and nutrient mobilization efficiency, indicating the requirement for standardization of formulation aligned to soil-specific conditions.

Drought stress severely impacts agricultural productivity, yet mechanisms underlying microbial enhancement of plant drought tolerance remain poorly understood. This study investigated whether Sphingobacterium nripensae DR205 exhibits drought-specific plant growth promotion through conditional metabolic activation. We combined plant cultivation experiments, genome sequencing, and comparative transcriptomics to evaluate DR205 responses under normal and drought conditions with or without root exudates. DR205 showed minimal growth promotion under normal conditions but enhanced plant biomass by 74–344% specifically under drought stress. Genome analysis revealed complete pathways for both stress tolerance (osmolyte biosynthesis and antioxidant systems) and plant interaction (IAA production and nutrient mobilization). Transcriptomics uncovered dramatic metabolic reprogramming under drought, with branched-chain amino acid (BCAA) biosynthesis genes shifting from 27-fold suppression under root exudates to 17-fold upregulation under drought. Lysine biosynthesis showed similar drought-specific activation patterns. Critically, drought signals overrode plant signals maintaining BCAA activation regardless of root exudate presence and ensuring metabolic investment in plant support occurred specifically during water deficit. This conditional mutualism represents a novel bacterial strategy where plant support is selectively activated during environmental stress. These findings challenge conventional PGPR paradigms and offer new approaches for developing climate-resilient agricultural systems through targeted application of stress-responsive beneficial microbes.

Arsenic contamination in agriculture negatively impacts the normal growth and development of plants, limiting crop production. Although plant growth-promoting rhizobacteria (PGPR) can enhance plant growth under stress, the molecular mechanisms of induced systemic tolerance (IST) exerted by these bacteria remain unclear. Thus, this study was designed to isolate arsenic-stress-tolerant PGPR from the rice rhizosphere to evaluate its effectiveness in rice plant growth and to understand the molecular mechanisms of IST against arsenite (AsIII) through jasmonic acid (JA) biosynthetic (OsAOS1), signaling (OsJAR1), and antioxidant (OsSOD-Cu/Zn, OsCATA, and OsAPX1) gene expression profiling. In this study, the arsenic-tolerant rhizobacterium RK027 was identified as Bacillus subtilis, exhibiting multiple PGP traits, including IAA, ammonia, and EPS production, phosphate solubilization, and ACCD activity, under both non-stressed and AsIII-stressed conditions. The FT-IR analysis of EPS revealed the presence of functional groups that likely form AsIII-EPS complexes, reducing AsIII translocation. Rice seed priming with RK027 and subsequent plant inoculation exhibited significant improvements in morphophysiological and biochemical traits, including antioxidant activities, during the vegetative and reproductive phases under both conditions. The qRT-PCR analysis indicated that B. subtilis RK027 significantly upregulated OsAOS1 (38% and 25%) and OsJAR1 (35% and 30%), OsSOD-Cu/Zn (59% and 78%), OsCATA (40% and 18%), and OsAPX1 (30% and 25%) compared to non-inoculated stressed plants in vegetative and reproductive phases, respectively. These enhancements suggest that B. subtilis RK027 exerts IST by enhancing JA-biosynthesis and downstream JA-responsive antioxidant pathways under AsIII-stress. Our findings highlight the potential of B. subtilis RK027 to improve rice plant health in arsenic-stressed environments.

Aims: The present study focused on exploring the potential of cyanobacteria in the bioremediation of organophosphorus (OP) compounds, also assessing the plant growth-promoting characteristics. Study Design: The study was conducted in three phases to evaluate the potential of selected cyanobacterial strains for bioremediation of organophosphorus (OP) compounds and their plant growth-promoting (PGP) properties. Place and Duration of Study: The work was carried out in Department of Microbiology, S. K. Porwal College of Arts, Science and Commerce, Kamptee for one and a half year. Methodology: Selected cyanobacterial isolates (Leptolyngbya) were cultured in BG-11 medium and exposed to organophosphorus (OP) compounds (chlorpyrifos) to assess degradation potential. Plant growth-promoting traits (IAA production, phosphate solubilization, and siderophore activity) were quantified using standard biochemical assays. Results: The results showed that blue-green algae (BGA) influenced both rice growth and soil properties. With the treatment of 20 ppm concentration, More than 85% degradation of chlorpyrifos was recorded within 20 days of incubation in samples treated with Leptolyngbya sp., whereas only minimal degradation was observed in the uninoculated control. Inoculated treatments exhibited higher plant growth and improved soil parameters compared to the control. Pot culture experiments indicated marked increases in growth attributes, including a 40% increase in plant height, 49% increase in root length, 40% increase in fresh leaf and stem weight, 49% increase in fresh root weight, 20% increase in dry leaf and stem weight, and 112% increase in dry root weight. Soil moisture content increased by 75% in inoculated pots relative to the control, overall which indicates sustainable and eco-friendly alternative in agriculture.

(1) Background: Oat (Avena sativa L.) is a crop that is widely used in human nutrition, while it also plays an important role in animal husbandry as a high-quality forage crop. However, this crop is particularly susceptible to combined biotic stressors, including insect pests (Agriotes lineatus) and fungal infections (Fusarium spp.). These stresses act synergistically: root damage caused by wireworms increases the plant's susceptibility to fungal infection, while pathogens further limit nutrient uptake and root system development. In recent years, the reduced efficacy of chemical pesticides against both insect pests and fungal pathogens has highlighted the need for alternative strategies in oat protection, leading to an increased focus on developing bacterial bio-inoculants as sustainable and effective biocontrol agents. (2) Methods: This study aimed to identify bacterial strains capable of suppressing wireworms (Agriotes lineatus) and Fusarium spp. in oats, while simultaneously promoting plant growth. Bacterial isolates were screened for key Plant Growth Promoting (PGP) and biocontrol traits, including IAA and siderophore production, phosphate solubilization, and the presence of toxin- and antibiotic-coding genes. (3) Results: The highest insecticidal effect against wireworms was recorded for Bacillus velezensis BHC 3.1 (63.33%), while this isolate also suppressed the growth of F. proliferatum for 59%, F. oxysporum for 65%, F. poae for 71%, and F. graminearum for 15%. The most effective Bacillus strains (with insecticidal and antifungal activity) were identified and tested in two pot experiments, where their ability to enhance plant growth in the presence of insects and fungi was evaluated under semi-controlled conditions. An increase in plant biomass, grain yield, and nitrogen content was observed in oat inoculated with B. velezensis BHC 3.1 and B. thuringiensis BHC 2.4. (4) Conclusions: These results demonstrate the strong potential of both strains as multifunctional bio-inoculants for enhancing oat growth and mitigating the adverse effects of wireworm damage and Fusarium infection.

Potato (Solanum tuberosum L.) is a key staple crop in the Peruvian Andes, but its productivity is threatened by fungal pathogens such as Rhizoctonia solani and Alternaria alternata. In this study, 71 native bacterial strains (39 from phyllosphere and 32 from rhizosphere) were isolated from potato plants across five agroecological zones of Peru and characterized for their plant growth-promoting (PGPR) and antagonistic traits. Actinomycetes demonstrated broader enzymatic profiles, with 2ACPP4 and 2ACPP8 showing high proteolytic (68.4%, 63.4%), lipolytic (59.5%, 60.6%), chitinolytic (32.7%, 35.5%) and amylolytic activity (76.3%, 71.5%). Strain 5ACPP5 (Streptomyces decoyicus) produced 42.8% chitinase and solubilized both dicalcium (120.6%) and tricalcium phosphate (122.3%). The highest IAA production was recorded in Bacillus strain 2BPP8 (95.4 µg/mL), while 5ACPP6 was the highest among Actinomycetes (83.4 µg/mL). Siderophore production was highest in 5ACPP5 (412.4%) and 2ACPP4 (406.8%). In vitro antagonism assays showed that 5ACPP5 inhibited R. solani and A. alternata by 86.4% and 68.9%, respectively, while Bacillus strain BPP4 reached 51.0% inhibition against A. alternata. In greenhouse trials, strain 4BPP8 significantly increased fresh tuber weight (11.91 g), while 5ACPP5 enhanced root biomass and reduced stem canker severity. Molecular identification confirmed BPP4 as Bacillus halotolerans and 5ACPP5 as Streptomyces decoyicus. These strains represent promising candidates for the development of bioinoculants for sustainable potato cultivation in Andean systems.

Cotton production is negatively affected by both biotic (diseases and insects) and abiotic (high temperature, salinity, water deficit, and extreme pH) factors. Soil-borne diseases, especially wilts and rots, significantly reduce cotton yield. Thus, we aimed to isolate and identify multi-stress tolerant bacterial antagonistic agents (AGAs) against two major soil-borne pathogens, Macrophomina phaseolina and Fusarium oxysporum. A total of 132 isolates with distinct morphologies were recovered from 25 different rhizospheric soil samples of cotton. A dual culture plate and broth assay confirmed the antagonistic activity of the isolates against these phytopathogens. Four selected AGAs thrived in salt stress induced by different NaCl concentrations, up to 1.71 M, except for isolate 62, which survived up to 0.85 M. Under osmotic stress, all the AGAs were tolerant of up to − 1.03 MPa. Similarly, all the AGAs were able to survive over a temperature range of 20–50 ◦C except for isolate 62, which survived up to 45 ◦C and was regarded as thermotolerant. All four AGAs were able to grow at pH values ranging from 5 to 9. AGA 18 and S46-7 survived under highly acidic conditions (pH 4). These multi-stress tolerant AGAs also exhibited different plant growth-promoting activities, such as mineral solubilization, ACC-deaminase production, and IAA production. Molecular identification revealed the following AGAs: Bacillus siamensis SSVP1 (18), Bacillus halotolerans SSVP2 (34), Pseudomonas aeruginosa SSVP3 (62), and Bacillus tequilensis SSVP4 (S46-7). AGAs with multiple stress tolerance traits can serve as potential biocontrol agents in the field to reduce pesticide consumption in cotton-growing areas.

Endophytes colonize host crops throughout their life cycle, such as seeds, where they play vital roles. This study investigated the seed endosperm microbiota of two wheat species (Triticum dicoccum and T. durum) using culture-dependent methods, assessing plant growth-promoting (PGP) traits under controlled conditions.The culturable microbial load in endosperms ranged from 86 ± 0.94 to 973 ± 13.52 CFU/g, with wheat seed medium supporting optimal recovery of culturable endophytes under the tested conditions. Forty-four bacterial isolates were obtained, and 16 were selected based on morphology, representing five genera: Bacillus (dominant), Pseudomonas, Pantoea, Saccharibacillus, and Pseudescherichia. These isolates tolerated abiotic stress (40°C, pH 9.0, 15% salinity, 15% PEG) and exhibit multiple PGP traits. Among them, 13, 2, 12, 3, 10, and 12 isolates showed phosphorus solubilization, potassium solubilization, IAA, siderophore, ammonia, and HCN production, respectively. Enzyme production was also notable; 13 produced amylase and cellulase, and 12 produced xylanase. Eight isolates showed antagonism against Fusarium graminearum, Bipolaris sorokiniana, and Tilletia indica. Notably, Pseudomonas aeruginosa CZ-45 exhibited high acetylene reduction activity (83.6 ± 0.6 nmol ethylene h⁻¹ mg⁻¹ protein), suggesting potential nitrogenase activity, though further molecular validation is warranted as nitrogen fixation is uncommon within this genus, phosphate solubilization (0.99mg/ml), and broad enzyme activity. Both P. aeruginosa CZ-45 and Pantoea agglomerans CZ-47 inhibited > 60% of all pathogens. Based on performance, six top-performing endophytes were selected as bio-inoculants. Notably, inoculation with Bacillus aryabhattai PZ-55 and Bacillus endophyticus PZ-40 significantly enhanced growth and biomass in both wheat species. These isolates have strong potential as bio-inputs to improve crop productivity.

Bacterial soft rot is a destructive disease that hinders the production of Amorphophallus konjac. In this study, a bacterial strain (GZY0) antagonistic to Pectobacterium aroidearum was isolated from the rhizospheric soil of A. konjac using the solid agar plate confrontation test. Through 16S rRNA sequencing, gyrA gene sequencing, and ANI analysis, this GZY0 strain was identified as Bacillus velezensis. The cell suspension and cell-free supernatant of GZY0 produced bacteriostatic inhibition zones with diameters of 15.63 and 16.70 mm, respectively, against P. aroidearum. Both in vitro antagonist assays and greenhouse pot experiments demonstrated that GZY0 is effective at controlling soft rot in A. konjac. During in vitro antagonistic tests in A. konjac tissues, mixed inoculation with the cell suspension or cell-free supernatant of GZY0 provided control efficacy of 47.56% and 45.79%, respectively, compared with the inoculation of a P. aroidearum bacterial suspension alone. Greenhouse pot experiments further validated its disease-preventing potential, the disease index of the GZY0 + P. aroidearum-coinoculated group was 45.81% lower than that of the P. aroidearum-inoculatedgroup. Additional functional studies revealed that strain GZY0 exhibits excellent plant growth-promoting properties and capable of producing phosphorus-solubilizing zones on both inorganic and organic phosphorus media, with diameters of 11.68 mm and 7.50 mm, respectively. On CAS iron-supplemented medium, GZY0 produces an orange-yellow halo with a diameter of 11.33 mm and an A/Ar ratio of 1.19. Furthermore, GZY0 turns Salkowski reagent red, with an IAA yield of 17.77 mg/L. Furthermore, GZY0 exhibited antagonistic effects against Botryosphaeria dothidea, Fusarium oxysporum, F. solani, F. oxysporum f. sp. panax, and Colletotrichum gloeosporioides. Whole-genome sequencing demonstrated that the genome length of GZY0 was 4053804 bp and included 3,934 coding genes. In order to elucidate the biocontrol mechanisms of strain GZY0, genes related to nitrogen fixation, phosphorus solubilization, and IAA and siderophore production were identified, and 12 antagonism-related secondary metabolite synthesis gene clusters and induced systemic resistance-related genes were predicted. A total of 5,169 pan-genes were detected in the comparative genome, all possessing open pan-genes and closed core genes. Additionally, 3,240 homologous genes were shared among the six Bacillus spp. strains, with GZY0 harboring 171 unique homologous genes. In summary, our findings demonstrated that GZY0 exhibits plant growth promotion capabilities and serves as a potential biocontrol agent for soft rot in A. konjac. Hence, this strain warrants further development and application.

Biopriming with halotolerant microbes enhances growth performance, resilience and rhizospheric microbial diversity of Solanum melongena under saline conditions.

Salinity stress on productive rice fields in coastal areas will have a negative impact on productivity through osmotic stress and nutrient deficiencies. Salinity stress causes high levels of Na and Cl in the soil, thus inhibiting phosphate absorption. Utilization of indigenous P-solubilizing bacteria from saline land is an alternative, environmentally friendly technology. The purpose of this study was to isolate and characterize P-solubilizing bacteria from saline rice fields. Soil samples were taken from the rice rhizosphere in Nyamplungsari Village, Peraturkan District, Pemalang Regency. Isolation and characterization were carried out at the Agronomy & Horticulture Laboratory, Faculty of Agriculture, UNSOED. The variables observed included P solubility index, P solubilizing ability, IAA production, and bacterial identification using the 16S RNA method. The results of the study obtained 7 isolates of P-solubilizing bacteria that had the ability to solubilize P and produce IAA. Isolate KF is a P-solubilizing bacterium that has the highest P-solubilizing ability and is identified as Priestia megaterium strain NRRL B-350. Priestia megaterium strain NRRL B-350 is a species of P-solubilizing bacteria that has the potential to be developed as a specific biological fertilizer for saline soil to increase the growth and yield of rice plants under saline stress.